The Swedish housing market: Trends and risks

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Rapport till Finanspolitiska rådet 2013/5 The Swedish housing market: Trends and risks Peter Birch Sørensen University of Copenhagen The views expressed in this report are those of the author and do not necessarily represent those of the Swedish Fiscal Policy Council.

Preface In December 2011 the Swedish Fiscal Policy Council invited me to prepare a report on recent trends and risks in the Swedish housing market. My background for accepting the invitation was my long-standing interest in the Swedish economy and Swedish economic policy and my research on the Danish housing market while I was serving as Chief Economist of the Danish central bank.

Most of the work on the report was carried out during the summer and fall of 2012. Section 5 of this report draws on joint research with my Copenhagen University colleague Michael Bergman who is also a former member of the Fiscal Policy Council. I am grateful to Michael for inspiring collaboration; his econometric skills were indispensable for the work reported in section 5. Thanks are also due to Georg Marthin and Johanna Modigsson for assistance in gathering some of the data used in the report. Finally, I want to thank John Hassler, Steinar Holden and Irma Rosenberg for constructive comments on earlier drafts of the report.

Studier i finanspolitik 2013/5 5 1 Introduction and outline of the report Since the mid-1990s real house prices in Sweden have more than doubled and they are now at a historically high level. This has raised concerns that the market for owner-occupied housing may be overvalued and that Sweden may be headed for a significant drop in house prices. Against this background, Sveriges Riksbank (2011) recently published an extensive report analysing trends in the Swedish housing market and discussing the resulting risks to economic and financial stability. The present report supplements the Riksbank report by offering some further perspectives on the Swedish housing market.

The basic issue is whether Swedish house prices are currently seriously overvalued. If that is the case, what are the future implications for the Swedish economy? In addressing these difficult questions, the report draws on the international literature on the economics of housing markets and presents some new estimates of long-run equilibrium house prices in Sweden.

The report is structured as follows: Section 2 reviews the long-term and recent trends in Swedish house prices and compares them to house price developments in other countries. The section also discusses whether real house prices can be expected to remain constant or to trend upwards in the long run. Section 3 discusses how we can measure whether house prices are in some sense overvalued so that we may speak of a “housing bubble”. The section reviews alternative theories of how housing bubbles may arise, and it offers an illustrative case study by describing the recent bubble and subsequent downturn in the Danish housing market.

The last part of the section considers whether there are signs of a genuine housing bubble in Sweden. Section 4 explains the concept of the user cost of owner-occupied housing and illustrates how estimates of the user cost may be used to evaluate whether house prices are out of line with the cost of rental housing and with disposable incomes. The section offers new estimates of the evolution of the ratio of user costs to rents and disposable incomes in Sweden. Section 5 turns to the difficult question of how to identify the so-called fundamental house price, that is, the equilibrium house price implied by rational economic behaviour.

The section describes two alternative ways of calculating the fundamental house price and presents some new estimates of the evolution of fundamental house prices in Sweden. It also analyses the empirical link between actual and fundamental house prices. Section 6 offers some further perspectives on Swedish house prices, discussing how various factors such as financial innovation, demographics, property taxes and housing supply constraints may have affected equilibrium house prices in recent years. The section also considers how a possible downturn in the housing market might affect economic and financial stability in Sweden.

The conclusions of the report are summarized in Section 7, and the technical appendix lays out the theoretical foundation for the concept of user cost of owner-occupied housing.

6 2 Swedish house prices in international perspective 2.1 The evolution of real house prices in Sweden Figure 2.1 shows the evolution of house prices in Sweden since 1952. From the early 1950s to the mid-1990s real house prices seemed to fluctuate around a roughly flat long-term trend.1 This was followed by an unusually long and strong boom in house prices. The boom was interrupted by the international economic crisis of 2008–09 which caused a temporary downturn in the Swedish housing market. However, the market quickly recovered and although house prices have recently showed some signs of weakening, they remain at a very high level from a long-term historical perspective.

Figure 2.2 illustrates the development of real house prices in the various regions of Sweden. The price increases since the mid-1990s have been particularly strong in areas with large cities. This is a phenomenon also observed in other countries where real house prices have gone up. Figure 2.1 Real house prices in Sweden 1952–2011 Source: Statistics Sweden and own calculations. 1 The real house price is the nominal price of single-family homes (“småhus”) deflated by the consumer price index. 50 100 150 200 250 52 56 60 64 68 72 76 80 84 88 92 96 00 04 08 12

Studier i finanspolitik 2013/5 7 Figure 2.2 Real house prices in the various regions of Sweden 1980–2011 Source: Statistics Sweden and own calculations. 2.2 A comparison with other countries Figures 2.3a, 2.3b and 2.3c show that Sweden was certainly not the only OECD country to experience a significant run-up in real housing prices prior to the international financial crisis in 2008–09. Indeed, countries like Ireland, UK, Norway and Spain experienced even stronger house price booms. However, Belgium, Norway and Sweden stand out as the countries with the mildest and the shortest housing market downturns during the crisis, whereas most of the other countries have seen deeper and more prolonged drops in real house prices.

Studier i finanspolitik 2013/5 9 that there is no evidence of a positive long-run trend in real house prices. Figure 2.4, taken from Shiller (2007), shows the evolution of real house prices in three countries for which very long time series have been constructed.2 Figure 2.4 The long run evolution of real house prices in the Netherlands, Norway and the United States Note: The index for the Netherlands shows the evolution of house prices in Amsterdam. The index for Norway shows the average price development in the four largest cities.

Source: Shiller (2007, Figure 4). According to Figure 2.4 real house prices went through several prolonged cycles during the century from around 1890 to the early 1990s, but without displaying any clear upward or downward trend.

The boom in house prices since that time and up until the recent financial crisis was quite extraordinary in a long run historical perspective. Figure 2.5 takes Shiller’s long run real house price index for the USA up to the present and also includes his index for real construction costs in America. In the second quarter of 2012 the real house price index stood at 113,2 as compared to a value of 100 in 1890, indicating a very modest increase over this period of more than 120 years. In the 60-year period from around 1920 to about 1980 real building costs did in fact increase significantly after having trended downwards for a long time, but today construction costs are considerably below the peak reached in the late 1970s.

2 The indices in Figure 2.4 attempt to adjust for changes in the quality of housing in various ways, but obviously it is very difficult to estimate the quality-adjusted change in house prices over such a long period. Englund (2011, p. 62) provides a useful discussion of the measurement problems involved in constructing a house price index.

10 Figure 2.5 Real house prices and real building costs in the United States Source: www.econ.yale.edu/~shiller/data.htm. Shiller’s view that real house prices are likely to remain relatively constant over the long run is shared by many other economists. The theory behind this view can be illustrated by Figure 2.6 where the stock of owner-occupied housing (H) is measured along the horizontal axis and the real house price (P) is measured on the vertical axis. The horizontal curve labelled LRS is the long run supply curve in the housing market. It shows the real marginal cost of producing a new housing unit, and we see that this cost is assumed to be constant.

As long as the price of existing houses exceeds the marginal cost of building a new house of similar size and quality, profit-maximizing construction firms will add to the housing stock by building new houses. In contrast, if the price of existing houses falls short of the cost of constructing a new house, the building industry will face a profit squeeze which will drive construction activity below the level needed to compensate for the depreciation of existing houses. As a consequence, the housing stock will shrink.

Studier i finanspolitik 2013/5 11 The vertical curves 0 and 1 are short run supply curves indicating the housing stock existing at a given point in time. The downward-sloping curves labelled 0 and 1 are demand curves showing how the demand for housing varies with the house price. What consumers really demand is a flow of housing services, but we can reasonably assume that the consumption of housing services is proportional to the stock of housing measured along the horizontal axis.

The annual cost of the housing service provided by a house with a market price P is cP, where c is the user cost of housing, defined as the housing cost per krona of housing wealth. The user cost depends on the mortgage interest rate, property taxes, maintenance costs etc., as explained in detail in Section 4. For a given value of c, the cost of housing services will be proportional to the house price P. A fall in P will then induce a greater demand for housing, as indicated by the negative slope of the demand curves in Figure 2.6. The demand for housing also depends on other factors such as disposable incomes.

If incomes go up, or if the interest rate (and thereby the user cost) goes down, the demand for housing will increase at any given level of house prices, and the demand curve for housing will therefore shift to the right. We can now illustrate the market forces that tend to keep house prices in line with real construction costs in the long run. Suppose the initial situation in the housing market is given by point 0 ∗ in Figure 2.6. This is a long-run equilibrium where housing demand equals housing supply and where the cost of building a new house is just equal to the cost of acquiring an existing house of the same size and quality.

In such a long-run equilibrium the construction of new homes is just sufficient to make up for the depreciation of the existing housing stock, thus ensuring that the aggregate housing stock remains constant over time.

Now suppose that, at time 1, disposable income goes up so that the housing demand curve shifts outwards from 0 to 1. In the short run the housing stock is fixed because it takes time for building activity to add to the existing stock. On impact, house prices must therefore increase from 0 ∗ to 1 to clear the housing market. In this new short-run equilibrium, the price of existing houses exceeds the cost of building new houses. This drives construction activity above the level necessary to compensate for depreciation of the existing housing stock. As additional housing units are added to the current stock, the short run supply curve SRS gradually shifts to the right so that house prices are gradually forced back towards their original level.

If no further disturbances occur, this adjustment process will continue until the housing market reaches a new long run equilibrium at point 1 ∗ in Figure 2.6. At this point the housing stock has increased, but prices are back in line with construction costs. Alternatively, suppose that at time t, where the housing market is in short-run equilibrium at point , disposable income falls back to its original level so that the demand curve also shifts back to 0. In the short run house prices must then fall from point to ′ where existing houses are now cheaper than new houses. Hence construction activity will fall below the level needed to maintain the housing stock, so the short-run supply curve will

12 gradually shift to the left. This process will continue until the housing market is back in the original long-run equilibrium 0 ∗ where house prices are again equal to construction costs.3 The view illustrated in Figure 2.6 that real house prices tend to be constant in the long run is shared by many economists, but it has also been challenged by many others. To understand the controversy, note that two key components of the cost of supplying a new house are the price of the land on which the building is erected and the cost of the labour needed to build the house. The horizontal long-run supply curve in Figure 2.6 implicitly assumes that land prices do not increase more than other prices and that labour productivity in the construction sector increases in line with productivity in other sectors.4 Consider first the likely evolution of land prices.

Since the total supply of land is fixed, it may be hard to increase the supply of land used for housing purposes without driving up the relative (real) price of land. If land is scarce, we would therefore expect the long-run supply curve in the housing market to have a positive slope, as depicted in Figure 2.7: when construction firms expand the supply of new housing, the total demand for land is likely to increase, and with total land supply being fixed, the real price of land must go up to clear the land market. Construction firms may react to this by economizing on the use of land, e.g.

by erecting taller apartment buildings, but there is probably a limit to the possibilities of substituting buildings for land in the housing sector. As economic growth raises the level of income, shifting the housing demand curve to the right, we would therefore expect the housing market to move up along a rising long-run housing supply curve due to an increase in the real price of land, as illustrated by the move from point 0 ∗ to point 1 ∗ in Figure 2.7. Moreover, the long-run output growth in other sectors is also likely to raise the total demand for land, thereby driving up its relative price.

In that case the real cost of supplying a new housing unit will go up even if the demand for land used for housing has not increased. In terms of Figure 2.7, the long-run housing supply curve will shift upwards from, say, 0 to 1. The long-run growth process may thus take the economy from the equilibrium 0 ∗ to an equilibrium like 1 ∗′ rather than 1 ∗ .

3 Figure 2.6 assumes that house prices adjust instantaneously to clear the market. Empirical work indicates that house prices only gradually adjust to equilibrate housing demand and housing supply (see section 3). Moreover, the analysis in Figure 2.6 does not account for the shifts in the housing demand curve which may occur if changes in actual house prices generate changes in the expected capital gains on houses. Hence the figure does not give a fully adequate picture of the short-run dynamics of house prices. Nevertheless, the figure does capture the long-run mechanism whereby house prices are driven back towards construction costs through adjustments in housing supply.

4 In the long run the wages of construction workers must increase at the same rate as wages in other sectors. Labour productivity in the construction sector must therefore grow in line with average labour productivity elsewhere in the economy to ensure the same growth rate of unit labour costs.

Studier i finanspolitik 2013/5 13 Figure 2.7 Dynamics of the housing market when land is scarce The other implicit assumption behind the horizontal long-run housing supply curve in Figure 2.6 is that labour productivity in the construction sector evolves in line with productivity in the rest of the economy. If productivity growth in the building industry is slower, we would expect that industry’s unit labour costs to rise at a faster rate than elsewhere in the economy, assuming that the wages of construction workers must increase at the same rate as the average wage level (since construction firms could not otherwise attract labour).

Construction costs would then tend to rise at a faster pace than the general price level. Figure 2.8 shows that construction costs in Sweden have in fact risen faster than consumer prices during the last decade. This could reflect a relatively weak rate of productivity growth in construction. Such a trend provides a further reason why the long-run supply curve in Figure 2.7 may shift upwards over time.

14 The measure of construction costs in Figure 2.8 does not include the price of land, but only the prices of labour, materials and overhead costs (including profit margins). As mentioned, the total cost of supplying a new house to the market also includes the price of the building site.

The opportunity cost of land used for housing may be approximated by the price of agricultural land. In the long run one would therefore expect a link between the price of residential land and the price of land used for agriculture. In Sweden the latter price has risen much faster than consumer prices since the mid-1990s, as shown in Figure 2.9.

Figure 2.9 Agricultural land prices and consumer prices in Sweden Source: Statistics Sweden. Figure 2.10 shows that construction costs (excluding the price of land) have also increased at a faster rate than consumer prices in Denmark. Moreover, we see that Danish land prices have risen much faster than consumer prices since around 1960, although at an uneven pace. This is consistent with the view that the total real cost of supplying a new housing unit will tend to increase over time due to rising real land prices. According to Figure 2.10 there has indeed been a clear upward trend in real house prices in Denmark since 1960.

Studier i finanspolitik 2013/5 15 The secular trend in the price of housing land depends on the overall scarcity of land in the country and on factors such as zoning laws and urban planning practices influencing the elasticity of the supply of sites for house-building. A country like the USA may still have large areas of vacant land that could be used for housing. Moreover, whereas countries like Denmark, Sweden and some other European countries have experienced relatively poor productivity growth in the construction sector, productivity in the American building industry seems to have evolved more favourably.

The costs of construction in the USA have also been kept in check by the stagnating real wages of common labour in America in recent decades (Shiller, 2007, p. 5). Since all these determinants of the cost of new housing may evolve in different ways in different countries, it would be surprising if real house prices displayed identical long-run trends across countries. In particular, the relative abundance of land in the USA may make sustained increases in real house prices less likely in that country.

To assess whether permanent increases in real house prices could really be sustainable, we may also consider the following simple model of the housing market, where c, P and H still denote the user cost, the real house price and the real housing stock, respectively, Y is real disposable income, and B is the share of expenditure on (owner-occupied) housing in household budgets: Housing supply (2.1) Housing demand (2.2) Equilibrium (2.3) Budget share of housing (2.4) Equation (2.1) assumes that housing supply H(P) is an increasing function of the real house price. The demand for housing is given by the function D(cP, Y) in (2.2), indicating that housing demand depends (negatively) on the cost of housing services, cP, and (positively) on disposable income.

Equation (2.3) is the condition for equilibrium between housing demand and housing supply, and (2.4) defines the budget share of housing expenses. Since the user cost c depends on interest rates and tax rates, it may be expected to be stationary in the long run, so in a long-run perspective we may assume dc=0. From equations (2.1) through (2.4) one can then show that ( ) (2.5) [ 1 ] (2.6) , , (2.7)

16 where dX indicates the absolute change in variable X, is the numerical elasticity of housing demand with respect to the cost of housing services, is the elasticity of housing demand with respect to real disposable income, and is the price elasticity of housing supply.5 On average over the long run, the growth rate of real income, dY/Y, is positive. The income elasticity of housing demand is also positive, and the numerical price elasticity of housing demand ( ) is generally a finite number. According to equation (2.5) the long run growth rate of real house prices will then be positive unless the supply of housing is infinitely elastic in the long run (that is, unless ).

The case of an infinitely elastic housing supply corresponds to the textbook case of a horizontal long-run housing supply curve depicted in Figure 2.6.

However, if economic growth creates a growing scarcity of building sites, the elasticity of housing supply is likely to be finite, corresponding to the upwardsloping long-run housing supply curve shown in Figure 2.7. In that case equation (2.5) predicts a secular increase in real house prices. But wouldn’t secularly increasing real house prices imply that housing expenses would absorb an ever-increasing share of household budgets (and hence be unsustainable?). According to equation (2.6) the answer is: not necessarily. For example, if the numerical income and price elasticities of housing demand are both equal to 1 – as they could well be according to the Swedish study by Brusewitz (1998) – it follows from (2.6) that the budget share of housing expenses will be constant over the long run even if the elasticity of housing supply is finite.

As mentioned, equations (2.5) and (2.6) assume that the real user cost of housing is stationary over the long run. In Figure 2.11 the real user cost of owner-occupied housing in Sweden is proxied by the real after-tax interest rate on 5-year mortgage loans plus a constant risk premium. We see that the user cost rose sharply in the early 1990s. This was due to a special combination of an increase in the nominal interest rate triggered by a foreign exchange crisis, a sharp drop in the expected inflation rate and a significant cut in the capital income tax rate. However, since the early 1990s the user cost has tended to move back towards the level prevailing in the 1980s.

This is consistent with the theoretically well-founded idea that the user cost is stationary in the long run. 5 In other words, measures the percentage decrease in housing demand in case of a 1 per cent increase in the real housing cost, is the percentage increase in housing demand generated by a 1 per cent increase in real income, and is the percentage increase in housing supply induced by a 1 per cent increase in the real house price.

Studier i finanspolitik 2013/5 17 Figure 2.11 The real user cost of owner-occupied housing in Sweden Note: The user cost is approximated by the real after-tax interest rate on 5-year mortgage loans plus a risk premium of 7 per cent. Source: Own calculations based on the data presented in Bergman and Sørensen (2012). As we saw, a secular increase in real house price does not necessarily imply a secular rise in the budget share of housing costs. In Figure 2.12 we have calculated the budget share of total owner-occupied housing costs from formula (2.4). We see that the rise in the user cost in the early 1990s forced Swedish households to spend a larger fraction of their income on housing, but overall Figure 2.12 suggests that the budget share of housing costs is in fact fairly stable over the long haul.

18 If user costs and the budget share of housing are both stationary, real house prices can only rise over time if the real housing stock grows at a slower pace than real disposable income.

As shown in Figure 2.14, this has in fact been the case in Sweden during the last quarter century. In summary, there may be an underlying tendency for real house prices to grow over the long run due to growing scarcity of land and possibly also because of relatively weak productivity growth in the building industry. A secular rise in real house prices does not require an ever-increasing share of housing expenses in household budgets, provided the real housing stock grows at a slower pace than real income.

Figure 2.13 The ratio of the real housing stock to real disposable income in Sweden Source: Own calculations based on the data presented in Bergman and Sørensen (2012). However, between 1995 and 2011 real house prices in Sweden grew at an average annual rate of about 5.7 per cent. When evaluating this number, we should keep in mind that the Swedish housing market reached a trough in 1995, so some recovery of house prices was to be expected. Nevertheless, an annual growth rate of real estate prices close to 6 per cent over such an extended period seems very high, considering the foregoing analysis of the likely secular trend in house prices.

For example, suppose we accept that over the long run, the following conditions must hold: 1) The real user cost of housing must be roughly constant. 2) The budget share of housing expenses must be roughly constant. 3) The real housing stock must be non-decreasing (assuming that the population is non-decreasing). Under these conditions, if the long run growth rate of real income is, say, 2 per cent per year, the maximum sustainable long-run annual increase in real house prices is also 2 per cent.

Moreover, before the mid-1990s Swedish real house prices did in fact seem to hover around a roughly constant trend, as we saw in Figure 2.1. Against this background it is reasonable to ask whether Swedish house prices are currently overvalued. The next main section discusses the concept of “overvaluation” and how overvaluation may come about. 20 40 60 80 100 120 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 1986:1=100

Studier i finanspolitik 2013/5 19 3 Housing bubbles: How do they arise? And how do we measure them? 3.1 What do we mean by a “housing bubble?” As noted by Claussen, Jonsson and Lagerwall (2011, p.

81), a statement like “Swedish house prices are overvalued” could be interpreted in various ways such as the following: i. House prices are above their long-term trend level ii. House prices cannot be explained by “fundamental” factors iii. Models of the housing market predict falling real house prices in the future Figure 2.1 does indeed suggest that Swedish real estate prices are currently above their long-run trend level, indicating that the market is overvalued according to definition (i). The weakness of this definition is that the estimated long-run trend in real house prices depends on the time period considered.

If we believe that the structure of the housing market has changed significantly since the early post-war decades, we might not want to include data for these decades in an estimate of the long-term trend in house prices. For example, if we only want to focus on developments after the liberalization of capital markets in the 1980s, a quick look at Figure 2.1 suggests that the underlying trend in real house prices may have become steeper since that time. However, because the position and slope of a fitted trend in house prices is so critically dependent on the time period selected, the use of such a trend line is a rather unsatisfactory way of estimating whether and by how much the housing market may be overvalued.

From a theoretical viewpoint it is better to measure the degree of overvaluation or undervaluation as the distance between actual and fundamental house prices, as suggested by definition (ii) above. The “fundamental” level of house prices is the level that can be explained by “fundamental” economic variables such as interest rates, disposable incomes, household wealth, property taxes etc. In applying this approach it is important to be clear about the time horizon considered. The reason is that it takes time for house prices to adjust to a short-run equilibrium where housing demand equals the existing housing stock, and it takes even longer time for the housing market to adjust to a longrun equilibrium where the prices of existing houses equal the cost of supplying similar new houses and where the expected rate of increase of house prices equals the actual rate.

In Figure 2.6 we made the simplifying assumption that house prices adjust instantly to establish a short-run equilibrium where the demand for houses equals the existing stock. In practice several factors prevent such instantaneous adjustment. Individual houses are heterogeneous goods, and it takes time for home buyers to find a house with the characteristics that fit their tastes and needs, just as it may take time for home sellers to find out what a realistic

20 selling price for their particular house might be in a declining housing market. Moreover, moving from one dwelling to another involves substantial transaction costs.

For these reasons we would expect that house prices will only gradually adjust to equilibrate housing demand and housing supply. The empirical evidence supports this view. For example, using data for Swedish regions, Hort (2000) found that the number of houses sold reacts faster than house prices to changes in economic fundamentals (such as interest rate changes). As another example, Genesove and Mayer (2001) presented evidence from the USA indicating that home sellers are reluctant to cut selling prices in a falling housing market. Traditional econometric error-correction models of the housing market also clearly suggest that it takes time for house prices to adjust to the market-clearing level even if (as a simulation experiment) the housing stock is held fixed.

At any point in time, the housing market may therefore be expected to be in a state of disequilibrium where house prices are headed towards the level that will bring the demand for housing in line with the existing housing stock (given the expected future capital gain on houses which is one of the determinants of housing demand, as we shall see in section 4). When this price level is reached, the housing market is in short-run equilibrium, since there will be no further downward or upward pressure on real house prices provided the housing stock and the expected capital gains stay constant.

A long-run housing market equilibrium is reached when house prices as well as the housing stock have adjusted to the level where the prices of existing homes equal the marginal cost of supplying similar new homes and expected capital gains equal actual capital gains.6 With these concepts of equilibrium in mind, we might say that the housing market is overvalued (undervalued) from a short-term perspective if the current level of house prices exceeds (is lower than) the estimated short-run equilibrium level. Similarly, we might say that house prices are overvalued (undervalued) from a long-term perspective if current prices are above (below) their estimated long-run equilibrium level.

Since it may take a decade or more for the housing market to adjust to a long-term equilibrium following a shock to the market, it is obviously important to specify which of the two concepts of equilibrium one adopts when evaluating the sustainability of current house prices. The analysis in sections 4 and 5 may be seen as alternative attempts to judge whether Swedish house prices are currently above their long-run equilibrium level.

According to the reasoning above there is really no difference between the definitions of “overvaluation” stated in the bullet points (ii) and (iii) in the beginning of this section. House prices could be said to exceed their fundamental values when they are above their (short-run or long-run) equilibrium level. If that is the case, any model of the housing market which is 6 If expectations were always rational, the expected capital gains would on average equal the actual gains even in a short-run equilibrium.

Studier i finanspolitik 2013/5 21 correctly specified and estimated will predict that house prices will fall in the future.

However, in some academic studies asset prices are said to be out of line with fundamentals only if they cannot be explained as the outcome of “normal” market dynamics. If this approach is adopted, a house price above the shortrun equilibrium level does not necessarily indicate that the housing market is overvalued, provided the current price level can be explained by the normal out-of-equilibrium dynamics of a standard (error-correction) model of the housing market. By definition (iii) above the housing market would still be overvalued, since they are predicted by the relevant model to fall in the future, but by definition (ii) there would be no overvaluation since the current high level of house prices can be explained by the usual market “frictions” that prevent an instantaneous adjustment of house prices to changes in fundamentals.

This distinction between definitions (ii) and (iii) leads us to what seems to be the most reasonable definition of a housing bubble – a term that is often used in a very casual manner: For the purpose of this report we shall define a housing bubble as a situation where house prices deviate significantly from the short-run equilibrium level implied by the current values of the relevant economic fundamentals and where this deviation cannot be said to reflect the normal disequilibrium dynamics of the market.

Standard definitions of asset price bubbles typically emphasize that a bubble exists when an asset price deviates from its fundamental value as a result of overoptimistic expectations about future price gains.

The point of our definition of a housing bubble is that a deviation of house prices from their fundamental short-run equilibrium level does not necessarily reflect a bubble. Because of high transaction costs and the search costs of matching buyers and sellers in the housing market, we would expect that house prices only gradually adjust towards the equilibrium level implied by current fundamentals. It is only when the deviation of prices from this level becomes abnormally high that we may be confronted with a bubble.

Clearly this definition of a “bubble” is not easy to apply in practice, since there is uncertainty regarding the (short-run) equilibrium price level as well as the “normal” pattern of disequilibrium price dynamics. The uncertainty is particularly large when the housing market undergoes structural change which alters the quantitative link between the fundamentals and the equilibrium price and/or the dynamic adjustment pattern. But regardless of the particular definition of “bubbles” adopted, history shows that asset price bubbles are quite hard to identify ex ante, at least until they have grown very large.

The motivation for our interest in bubbles is the well-known fact that asset prices typically fall very quickly and dramatically when a big bubble bursts and prices move back towards their fundamental level. Indeed, markets often appear to overreact in the aftermath of a bubble, driving prices to “unreasonably” low levels below what seems justified by fundamentals. As an example of how a housing bubble may play out, we will now look at the recent Danish housing market experience. We will then consider various ways in

22 which a housing bubble may arise. In the final part of the section we will briefly discuss whether Sweden currently has a housing bubble. 3.2 A case study: The Danish housing bubble in the 2000s As shown in Figure 2.3a, the rise in real house prices in Denmark was extremely steep in 2005–2006. The econometric models of the Danish housing market existing at the time grossly underestimated the rise in house prices even when the actual observed values (and not just the forecasted values) of the explanatory variables were plugged into the models. This remarkable episode motivated a team of researchers in Danmarks Nationalbank to develop a new econometric model of the Danish market for owner-occupied housing.

Existing models had assumed that housing demand depends on real disposable income plus a conventional measure of the user cost of housing. The new model developed by Danmarks Nationalbank, presented in Dam et al. (2011), assumed instead that home buyers react to a measure of cost which is a weighted average of the traditional user cost and the minimum necessary firstyear cash flow payable by a fully leveraged home buyer. This minimum firstyear payment includes after-tax nominal interest payments, property taxes plus any amortization required, given the most liberal mortgage loan types available at the time of purchase.

There may be two reasons why home buyers may be willing to pay a higher price if the required first-year payment goes down, say, through the offering of interest-only loans. First, some home buyers may be credit-constrained which makes lower cash flow expenses here and now attractive. Second, some home buyers may simply be myopic, not realizing or caring that lower amortization of mortgage debt today will increase total mortgage payments tomorrow.

By including the minimum required first-year payment in the measure of the cost of housing services, it was possible to achieve a better explanation for the evolution of Danish house prices. Nevertheless, although the new housing model tracks the actual development of house prices quite well up until the middle of the previous decade, it still underpredicts the rise in house prices in 2005 and 2006. This is illustrated in Figure 3.1 which shows the actual level of real house prices and the level predicted by a dynamic simulation of the estimated model.7 7 The model is of the error-correction type, allowing for a gradual adjustment of actual prices to the level needed to equate the underlying housing demand with the existing housing stock.

Thus the current house price depends in part on lagged house prices. The dynamic simulation in Figure 3.1 uses the lagged house prices predicted by the model (rather than the actual lagged prices) to calculate the price level in subsequent periods.

Studier i finanspolitik 2013/5 23 Figure 3.1 Actual and estimated real house prices in Denmark Source: Simulation by Danmarks Nationalbank (2012, p. 27) based on the housing market model presented in Dam et al. (2011). We also see that, following the sharp downturn in 2008–2009 and the further fall in 2011, Danish house prices are now considerably lower than predicted by the model. A natural interpretation of these data is that Denmark experienced a genuine housing bubble in the middle of the last decade: even the best available models of the housing market failed to predict the strong upturn and the subsequent sharp downturn of house prices.

Consumer surveys as well as casual evidence suggest that the upturn was driven by exuberant expectations of future capital gains on houses and that consumers became quite pessimistic about future price developments after the downturn. The housing market model described above assumes that expected future capital gains on houses are determined by a weighted average of actual past gains, but the model apparently fails to capture the volatile dynamics of expectations in recent years. Again, such rapidly shifting expectations seem to be characteristic of most bubble episodes across countries and time.

The soaring Danish house prices in the mid-2000s stimulated consumer demand (through its positive impact on household wealth) and housing investment and contributed significantly to the overheating of the Danish economy in 2006–2007. As a result of record-low unemployment, wage inflation accelerated, undermining the international wage competitiveness of Danish firms. When the housing bubble burst, construction activity and consumer confidence collapsed at the same time as Danish net exports suffered from the combination of the international economic crisis and weaker cost competitiveness. Concerns among international investors that the Danish housing market had become seriously overvalued also made it more difficult for Danish banks to obtain international funding as the international financial crisis unfolded.

Thus the Danish housing bubble undoubtedly helps to explain why the growth of the Danish economy has been so anaemic over the last few years.

24 3.3 How do housing bubbles arise? Since housing bubbles and their bursting can cause so much economic damage, it is useful to have an idea of how they arise. An extensive survey of alternative theories of housing bubbles is beyond the scope of this report, but below we will briefly sketch some of the bubble theories that have been offered in recent years. Asset price bubbles are often seen as evidence of irrational market psychology, but in fact bubbles are not necessarily inconsistent with rational expectations and optimizing investor behaviour. The reason is that the price of an asset today depends in part on its expected price tomorrow, that is, on the expected capital gain.

In a rational frictionless housing market, a house will trade at a price equal to the discounted value of the future housing services it produces, provided house prices are not expected to increase at a rate exceeding the discount rate (see section 5). The discounted value of future housing services is the fundamental house price. But suppose that for some reason market agents believe that house prices will rise at a rate exceeding the discount rate. The current house price will then exceed the fundamental price by a “bubble” component which will grow over time as long as the expectations of large price gains persist.

In this situation the housing market can be in a rational expectations equilibrium where price expectations are validated as house prices are continuously bid up by anticipations of further price hikes. One might object that truly rational house buyers would not expect house prices to rise at a high rate forever, anticipating that houses would ultimately become so expensive that no one could afford to buy them. But if interest rates are low, the expected rate of house price inflation could exceed the discount rate even if it does not exceed the expected rate of income growth, so in a low-interest rate environment houses would not necessarily end up being prohibitively expensive even if there were a bubble in house prices.

Moreover, even if market agents expect that an asset bubble will burst with a certain probability in each period, it could still be rational for them to invest in the asset if the expected capital gain in case the bubble does not burst is sufficiently high, as shown by Blanchard (1979).

Arce and López-Salido (2011) demonstrate how housing bubbles can arise under rational expectations when there are minimum collateral requirements tying the borrowing capacity of homeowners to the value of their houses. By limiting the volume of debt, collateral constraints restrict the supply of assets in the economy. In case of a large positive “funding shock” that increases the availability of credit, the interest on debt instruments may then become so low that it becomes more attractive for wealth owners to invest in houses for purely speculative purposes, that is, without actually living in them.

Such speculative investment can fuel a housing bubble where house prices become detached from the discounted value of housing services. This confirms that housing bubbles are more likely to occur in a low-interest rate environment. In recent years scholars working in the field of behavioural finance have developed an alternative to the theory of “rational bubbles”. These researchers draw on insights from psychology and social psychology to explain features of